Why Senate Polling Is Always Worse in Summer

Patrick Ruffini: “In the last few election cycles, we’ve seen a pattern of Democrats looking competitive in red state Senate contests during the summer only to fade by election day. I wanted to test if this was a consistent pattern, not just the selective memory of a Republican.”

“3,312 polls over the last four election cycles in the old FiveThirtyEight archive confirmed the pattern. In each of those four cycles, the Democratic candidate’s margin was overstated. The average polling error across all polls was D+3.7, and 73% of polls released overstated the Democrat relative to the election result. Again, that’s across more than 3,000 polls, so that’s hardly just statistical noise.”